Lean Gasoline Engine Emission Challenges

Transcription

1 Lean Gasoline Engine Emission Challenges Jim Parks, Dean Edwards, Shean Huff, John Thomas, Kevin Norman, Vitaly Prikhodko, Bill Partridge, Jae-Soon Choi, Paul Chambon, John Storey, Teresa Barone Oak Ridge National Laboratory A Note on Recent Database Upload to the CLEERS Website CLEERS Workshop April 21, 2011 Sponsors: Gurpreet Singh and Ken Howden Advanced Combustion Engine Program U.S. Department of Energy

2 Background Relevance: U.S. passenger car fleet is dominated by gasoline-fueled vehicles. Enabling introduction of more efficient lean gasoline engines can provide significant reductions in passenger car fuel consumption thereby lowering petroleum use and reducing greenhouse gases lean gasoline is one of many options being considered, but it is an option that has synergy with other technologies (e.g. HEVs) Experimental Studies: ORNL studied a modern lean gasoline vehicle (BMW 120i) on a chassis dynamometer Fuel saving benefits of the lean combustion were characterized Combustion (AFR, etc.) and emissions data were also collected Database: Engine map data with emissions has been uploaded to the CLEERS website 2 Managed by UT-Battelle

3 BMW 120i Lean Gasoline Vehicle Thanks to GM for loan of vehicle Engine Out 1 2 LNT In TWC LNT Managed by UT-Battelle TWC LNT Out Engine Specs (N43B20): 2.0- Liter 4- cylinder Lean burn combusdon 200 bar direct InjecDon 170 hp (130 kw) at 6,700 rpm 210 Nm (155 N- lb) at 4,250 rpm 12:1 compression rado Dual VVT and EGR

4 Lean Engine Operation Gives Primary Fuel Economy Benefit but Does Not Meet U.S. Emission Regulations 2008 BMW 1 Series Fuel Economy Vehicle has multiple technologies for fuel economy improvement Lean operation offers most significant fuel economy improvement Start/Stop operation and mild hybridization via intelligent alternator control also contribute to fuel economy improvements 2008 BMW 1 Series - NOx Emissions MPG Stoich. Lean Lean with Start/Stop Lean, Start/Stop & Smart Alt FTP HFET US06 g/mi US Tier II Standard 50k Bin 5 = 0.05(g/mi) EU Standard (new vehicle) Euro4 = 0.13 (g/mi) Stoich Lean Lean & micro hybrid Lean engine improves fuel economy but fails to meet US emission standards Managed by UT-Battelle 0.03 FTP HFET US06

5 4-15% Fuel Economy Benefit from Lean Combustion but NOx Emissions Problematic during Lean Mode Vehicle designed to meet emissions levels required by European regulations NOx emission levels exceed U.S. Tier II Bin 5, 0.05 g/mile at 50k miles Bin 2 à 0.02 g/mile NOx emissions during lean operation are problematic Particulate matter (PM) emissions may also be of concern with respect to particle number regulations* *see SAE , SAE , SAE , etc. Improved Lean NOx catalysis required for deployment of lean gasoline vehicles 5 Managed by UT-Battelle Drive Cycle Fuel Economy Improvement** Tailpipe NOx emissions (g/s) Lean Stoich NOx Emissions (g/ mile) FTP 10.0% 0.11 HFET 14.6% 0.11 US06 4.4% 0.35 **comparing stoichiometric operation to lean

6 A Note on Analytical Tools Used in Study Emissions and Reductant Species UEGOs for both exhaust manifold legs General emissions analyzers at engine out and tailpipe positions Reductant focused emissions analysis at LNT inlet position FTIR (NO, NO 2, N 2 O, NH 3, HCs, CO, etc) Mass Spectrometry (SpaciMS) (H 2, O 2 ) Engine Out 1 2 TWC LNT In LNT Out 3 LNT 4 TWC 6 Managed by UT-Battelle

7 Database Uploaded to CLEERS Website 7 Managed by UT-Battelle

8 Files Uploaded to CLEERS Website Recent CLEERS telecon presentation uploaded for reference information (3) Excel files uploaded containing data as function of engine maps Lean operation Rich operation Merged data set Matlab m-file used for translation of engine shaft work to wheel work (transmission factor) Experiments were performed on vehicle on chassis dynamometer Fixed gear operation for steady-state engine map data A translation factor was applied to determine engine shaft work from the wheel work (measured) M-file generated for translations supplied here for users who may want to perform system level modeling (Autonomie, etc.) Many thanks to Dean Edwards and Paul Chambon for their work on this data set 8 Managed by UT-Battelle

9 Files Uploaded to CLEERS Website Data includes: Engine data such as AFR, air flow, fuel consumption, etc. Engine out emissions (CO 2, CO, O 2, THC, NOx) TWC Out/LNT In emissions (includes NO/NO 2, some HC speciation) Tailpipe emissions (CO 2, CO, O 2, THC, NOx) Exhaust system temperature and pressure data PM emission data Note: sparse non-replicated PM data (use with caution) Engine map data forced to square data matrices for ease of use in matrix math programs by filling edge regions with max, min, or interpolated values The filled data is noted by the font color red 9 Managed by UT-Battelle

10 Conclusions Chassis dynamometer study of a lean gasoline engine vehicle (BMW 120i) Fuel economy improvements from lean operation (vs. stoichiometric) were 4-15% and varied with drive cycle, but U.S. Tier II Bin 5 NOx emission level were exceeded Database of engine emissions and operational parameters (including emissions at various points in exhaust system) has been uploaded to CLEERS website Questions: Jim Parks parksjeii@ornl.gov (865) Managed by UT-Battelle